We request funds to purchase a system of four instruments for the core laboratory facility of our physiology research group consisting of 8 faculty investigators, 6 of whom have NIH grants. (In addition, 5 postdoctoral fellows and 7 doctoral candidate graduate students will use this equipment.) The specific equipment requested is as follows. 1) Blood Gas Analyzer. (Radiometer Model ABL4, or equivalent). 2) 8-Channel Strip Chart Recorders, Two each (Gould Model MK 200A),. 3) Liquid Scintillation Counter (Packard Tri-Carb Model 2200 CA). These instruments will be integrated in our data acquisition and analysis system. Our long-term objective is to pursue specific research studies including: 1) The Regulation of Fetal Oxygenation. The Dynamics and regulation of oxygen delivery to the fetus in utero, Functional development of cerebral and pulmonary blood vessels in the fetus and newborn, Thermal regulation in the fetus, Regulation of fetal breathing, Mathematical modeling of fetal circulation. 2) Neuroendocrine Development in the Fetus and Newborn: Development of hypothalamic- pituitary interrelations, Circadian rhythms in the fetus and mother, Hormonal regulation of the onset of labor, The endocrine regulation of the fetal cardiovascular system, Neuroendocrinology of sexual maturation, and Regulation of placental growth. These studies using both in vivo and in vitro techniques explore fundamental problems of broad biologic scope. Individual projects have led to significant increments in our knowledge of physiologic regulating mechanisms of the fetus and newborn. They also offer a basis for greater understanding of how these mechanisms apply to a variety of clinical problems in which the fetal and newborn endocrine and cardiovascular systems are stressed. The research studies performed during the past decade by the principal investigators in the Division have resulted in over one hundred and fifty publications in peer-reviewed scientific journals.